Hyphenation of 2D NMR With Hydrogenative PHIP

Abstract

Parahydrogen induced polarisation (PHIP) is often used to enhance the sensitivity of NMR, with the purpose of extending the applicability of the technique. Nuclear spin hyperpolarisation obtained via PHIP is generally localised on the protons derived from the addition of para-enriched hydrogen to an unsaturated substrate. This limitation has been previously addressed by pulse schemes that can spread this hyperpolarised magnetisation through the entire network of J-coupled protons in the product molecule. Here, we extend this approach, by implementing 2D NMR spectroscopy on such network of hyperpolarised protons. This novel approach to 2D acquisition during parahydrogenation allows information to be gained from the entirety of a molecule, quicker and/or at lower concentrations than by conventional NMR. The efficacy of the method is exemplified by performing a 2D TOCSY experiment during hydrogenative PHIP, using 2-pentyn-1-ol as a substrate. A 2D spectrum was obtained in a few minutes at micromolar concentration, demonstrating the applicability of this methodology.